// ========================================================================
// Copyright (c) 2004-2009 Mort Bay Consulting Pty. Ltd.
// ------------------------------------------------------------------------
// All rights reserved. This program and the accompanying materials
// are made available under the terms of the Eclipse Public License v1.0
// and Apache License v2.0 which accompanies this distribution.
// The Eclipse Public License is available at 
// http://www.eclipse.org/legal/epl-v10.html
// The Apache License v2.0 is available at
// http://www.opensource.org/licenses/apache2.0.php
// You may elect to redistribute this code under either of these licenses. 
// ========================================================================

package org.eclipse.jetty.util.ajax;

import java.lang.reflect.Method;
import java.util.Map;

import org.eclipse.jetty.util.Loader;
import org.eclipse.jetty.util.ajax.JSON.Output;
import org.eclipse.jetty.util.log.Log;
import org.eclipse.jetty.util.log.Logger;

/* ------------------------------------------------------------ */
/**
 * Convert an {@link Enum} to JSON. If fromJSON is true in the constructor, the JSON generated will be of the form {class="com.acme.TrafficLight",value="Green"} If fromJSON is false, then only the string value of the enum is generated.
 */
@SuppressWarnings({ "unchecked", "rawtypes" })
public class JSONEnumConvertor implements JSON.Convertor
{

	private static final Logger LOG = Log.getLogger(JSONEnumConvertor.class);
	private boolean _fromJSON;
	private Method _valueOf;
	{
		try
		{
			Class e = Loader.loadClass(getClass(), "java.lang.Enum");
			_valueOf = e.getMethod("valueOf", new Class[] { Class.class, String.class });
		} catch (Exception e)
		{
			throw new RuntimeException("!Enums", e);
		}
	}

	public JSONEnumConvertor()
	{
		this(false);
	}

	public JSONEnumConvertor(boolean fromJSON)
	{
		_fromJSON = fromJSON;
	}

	public Object fromJSON(Map map)
	{
		if (!_fromJSON)
			throw new UnsupportedOperationException();
		try
		{
			Class c = Loader.loadClass(getClass(), (String)map.get("class"));
			return _valueOf.invoke(null, new Object[] { c, map.get("value") });
		} catch (Exception e)
		{
			LOG.warn(e);
		}
		return null;
	}

	public void toJSON(Object obj, Output out)
	{
		if (_fromJSON)
		{
			out.addClass(obj.getClass());
			out.add("value", obj.toString());
		}
		else
		{
			out.add(obj.toString());
		}
	}

}
